Work supporting mechanism for grinding machines



W. F. FRASER Oct. 20, 1931.

WORK SUPPORTING MECHANISM FOR GRINDING MACHINES Filed Sept. 8, 1927 2 Sheets-Sheet i ATTORNEY.

Oct. 20, 1931. w. F. FRASER 1,828,530

WORK SUPPORTING MECHANISM FOR GRINDING MACHINES Filed Sept. 8, 1927 2 Sheets-Sheet 2 I N VEN TOR.

fl; A TTORNEY.

Patented Oct. 20, 1931 PATENT OFFICE WARREN IF. FRASER, OF WESTBORO, MASSACHUSETTS WORK SUPPORTING MECHANISM FOR GRINDING MACHINES Application filed September 8, 1927. Serial No. 218,196.

This invention relates to mechanisms for grinding or otherwise'operating on metal parts. 7 D

The invention is especially concerned with U the problem of finishing or shaping hollow articles of work in which the outer surface must be finished very accurately with reference to the inner surface or bore. For example, in making certain types of bearing bushings or guide bushings the outer surface must be made very closely concentric with the bore.

The present invention aims toreduce the labor and expense involved in making parts 18 of this general character.

The objects and nature of the invention will be better understood from the following description and by reference to the accompanying drawings, in which Figure 1 is a front elevation showing part of an automatic grinding machine embodying this invention, but in which only those parts required for an understanding of the invention are illustrated;

Fig. 2 is a horizontal cross-sectional view on the line 22, Fig. 1, showing the work supporting parts in the relation which they occupy during the grinding of the work;

Fig. 3 is a view similar to Fig. 2, but showing the parts during the operation of receiving or discharging the work; and

Fig. 4 is a view partly in horizontal crosssection illustrating a prior art arrangement for supporting the work during the grinding operation.

Certain objects of the invention will be best understood by considering briefly the usual practice heretofore employed in grinding bushings and similar articles of work. A typical apparatus used for this purpose is shown in Fig. 4:. The procedure conslsts 1n forcing an arbor or mandrel 2 into the bore of the bushing or other article of work W, and then clamping a driving dog 3 of a common type on one end of the arbor, this dog having a part designed to be engaged and driven by a portion of the revolving head stock of the machine. The mandrel with the bushing on it is next placed between centers l 50 and 5 and is revolved rapidly while the grinding wheel 6 is brought into contact with it.

mandrel and dog is taken out of the machine,

the dog is removed and the mandrel in pressed out of the bushing W.

It will beobserved that this method involves a number of operations which must be manually performed and consequently is relatively expensive. Furthermore, this method is applicable only with considerable difficulty to automatic grinding machines. Accordingly, it is an important object of this invention to simplify the operations required in grinding or otherwise shaping work of this character, and to reduce the time and labor involved in making bushings or other parts having bores. It is a further object of the invention to devise means for handling work of this character in an automatic machine.

Referring noW to Figs. 1, 2 and 3 the mechanism there shown comprises a grinding wheel 6 mounted on a head 7 which is supported on suitable ways provided on the machine frame or bed so that the wheel can be reciprocated toward or from the work, this being a common arrangement iii-grinding machines.

The bushing or other article of Work W is supported by two tapered members 9 and 10, see Figs. 2 and 3, which are formed on, or supported in, spindles 11 and 12, respectively. These spindles are mounted in axial alinement with each other and are supported for rapid rotation in bearings 13 and 14. They are also provided with pulleys to receive driving belts 15 and 16, respectively. Collars 1717 on the spindle 11 cooperate with parts of the bearing 13 to hold this spindle against longitudinal movement, but the spindle 12 is mounted to slide axially in its bearings toward or from its cooperating spindle to permit the introduction or removal of the workbetween the work supporting members 9 and 10.

In order to produce this movement the spindle 12 is provided with spaced collars 1818to receive a roll 19 between them, this roll being mounted on one arm of a bell crank lever which is fulcrumed on a rock shaft 21. A link 22 connects this lever with an arm 23 fast on the rock shaft 24, while another arm 25 which is secured to this rock shaft carries a roll 26 which runs on the face of a cam 27. A spring 28 acts on the arm 23 in a direction to hold the roll 26 in contact with the cam. The cam is secured on a shaft 29.which is driven in timed relationship to the other mechanisms in the machine.

It will be evident that at a certain time in the cycle of operations of the machine the cam 27 will operate through the mechanism above described to move the spindle 12 toward the right, Figs. 1, 2 and 3, and that it will be held in this retracted position for a period of time depending upon the dwell provided in the cam. During this period the ushing W may be placed between the two work supporting members 9 and 10, this work presenting movement being performed either manually or by automatic mechanism, as desired. The spring 28 next moves the spindle 12 toward the left as rapidly as the cam 27 will permit, thus producing a relative approaching movement of the two work supporting members 9 and 10. During this movement the tapered ends of these members enter the bore at opposite ends of the bushing and they are forced tightly into the bushing by the spring 28. By making the parts 9 and 10 on a gradual or slow ta er, they will fit tightly into the opposite en s of the bushing and thus will not only center the bushing but will also provide a driving engagement with it.

The work holding members 9 and 10 revolve rapidly so long as the machine remains in operation, and consequently, they pick up the bushing W and begin to revolve it rapidly as soon as they make a firm engagement with it. The grinding wheel 6 next is brought into contact with the bushing, it grinds the outer surface to the desired diameter, and is withdrawn again. The cam 27 next produces another receding movement of the spindle 12 relatively to its cooperating spindle 11 to permit the removal of the work.

Due to the fact that the tapers on the parts 9 and 10 are very gradual, one tapered member or the other will stick in the bushing so that it is necessary to provide some means for releasing the work from both of the members 9 and 10. An important feature of this invention resides in the mechanism provided for this purpose.

This mechanism comprises two strippers 31 and 32, respectively, which are designed to engage the work and remove it or strip it from the respective work supporting members 9 and 10. Each of these devices conslsts of a sleeve-like portion encircling its cooperating work supporting member. The stripper 32 is grooved to receive the lower forked end of a stationary plate 34 which is secured to the left-hand end of the bearing 14. Consequently, when the spindle 12 and its work supportin member 10 are moved toward the right the stripper 32 will move with it until it strikes the plate 34. Further movement of the stripper is arrested at this point, and as the work supporting member 10 continues to move, the bushing W, if it has stuck to this member, will be stripped off.

The stripper 31 is grooved to receive two rolls mounted in the lower forked end of a lever 35 which is fulcrumed at 36 on the hearing bracket 13. A hole is provided in the upper end of this lever, as shown in Fig. 1, to receive a slidable rod 37 on which two collars 3838 are adj ustably mounted at opposite sides of the lever arm 35. The rod 37 is pivoted to an arm 10 which is secured on the rock shaft 21, previously referred to. Consequently, when this rock shaft is operated b the cam 27 or spring 28, as above describe to produce the relative approaching and receding movements of the work supporting members 9 and 10, the stripper 31 also will be moved axially with reference to its work supporting member 9. When the receding movement of the spindle 12 occurs, the stripper 31 is moved toward the right, Figs. 1, 2 and 3, and thus forces the bushing W off the tapered part of the member 9. The relative receding movement of the two work supporting members 9 and 10 thus is utilized to remove the work from these members so that before this relative movement has been completed the work is removed and the machine 1s ready to receive a new piece of work. As the relative advancing movement of the two spindles occurs, the stripper 31 is moved toward the left and the stripper 32, after moving forward a short distance with its spindle 12, is then prevented by the plate 34 from following this movement further so that both strippers are held in backward or withdrawn positions where they will not interfere with the proper engagement of the members 9 and 10 with a new piece of work.

It will now be appreciated that this invention provides a very simple mechanism for centering and driving bushings and other hollow articles of work in a grinding or similar machine. The invention reduces very materially the time and labor involved in placing articles of work of this character in a grinding machine or removing them from it, and it is of particular utility in an automatic grinding machine since it is admirably adapted to cooperate with a mechanism for automatically presenting the articles of work one at a time between the spindle ends 9 and 10.

While I have herein shown and described a preferred embodiment of my invention it will be understood that the invention may be embodied in other forms without departing from the spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. In a machine for operating on metal articles of work having bored ends, the combination of two rotatable work supporting members having portions adapted to enter the holes in opposite ends of an article of work and to center said article, one of said members being tapered to fit tightly in the hole and drive the work, mechanism for rotating the latter member, means for moving said driving member axially toward and from the ot er work supporting member to engage and disengage the work, strippers for releasing the work from both of said members, parts supporting one of said strippers for operative movement relatively to its cooperating work supporting member, and connections between said means and the latter stripper for operating it.

2. In a machine for operating on metal articles of work having bored ends, the combination of two rotatable work supporting members having portions adapted to enter the holes in opposite ends of an article of work and to center said article, one of said members being taperedto fit tightly in the hole and drive the work, mechanism for rotating the latter member, means for moving said driving member axially toward and from the other Work supporting member to engage and disengage the work, said means including a lever for moving said member and a cam for operating said lever, strippers cooperating with sald work supporting members to remove the work from them, parts supporting one of said strippers for operative movement relatively to its respective work supporting member, and connections between the latter stripper and said lever for operating the stripper.

3. In a machine for operating on metalieces of work having bored ends, the comiiination of two rotatable work supporting spindles having gradually tapered ends to enter the holes in the opposite ends of the work to center and drive the work, means for rotating said spindles, mechanism for producing relative approaching and receding movements of said spindles to cause them to engage and disengage the work, and strippers cooperating with said spindles to utilize the relative receding movement of said spindles to disengage the work from said tapered ends of the spindles.

4. In a machine for operating on metal I pieces of work having bored ends, the combination of two rotatable work supporting spindles having gradually tapered ends to enter the holes in the opposite ends of the work to center and drive the work, means for rotatin said "spindles, mechanism for producing re ative approaching and receding movements of said spindles to cause them to engage and disengage the work, two strippers 

